Linköping University | IEI – Department of Management and Engineering Master thesis report 30 HP | Civilingenjör - Design and Product Development
Fall term 2015 |LIU-IEI-TEK-A--16/02437—SE
Planning Interior Lighting in a Truck Cab
A thesis in visual ergonomics
Authors: Erik Asp och David Järlstig
Supervisor: David Eklöf
Examiner: Kerstin Johansen
Linköpings universitet SE-581 83 Linköping, Sweden
Preface
This thesis was written at the department for physical vehicle ergonomics at Scania CV AB in Södertälje. We are very thankful for the opportunity to write this thesis at Scania and all the help we got, especially at the department of physical vehicle ergonomics, but also from other departments at Scania.
We would like to give a special thanks to our supervisor Stefan Uddholm, who has been a great support while writing this thesis. He has always been willing to answer questions and guide us at Scania.
We would like to thank our supervisor David Eklöf at Linköping University for good discussions and feedback on our thesis. Also our examiner Kerstin Johansen for great feedback.
We would like to thank Per Nylén, at Arbetsmilöverket for sharing his knowledge in visual ergonomics and lending us a luminance meter.
We would like to thank Michael Hallbert for inspiration and teaching us about lighting design.
Abstract
A long-haulage truck cab from Scania is an environment that involves various activities and combines a working place with compact living which sets different requirements on the lighting environment depending on the activity. Truck drivers have different requirements in means of visual ergonomics and preference on the lighting design. A conclusion in this thesis is that different user in various activities sets different requirements on lighting design in a truck cab.
Lighting planning in a truck cab with new lighting technologies such as LED (Light Emitting Diode) and OLED (Organic Light Emitting Diode) stands for a paradigm shift in lighting planning and lighting design. The new technologies enables more integration in the interior, more diverse lighting which means more effort is needed to succeed in good visual ergonomics, light distribution, aesthetic expression and branding.
Studies have shown that by blue enriched light can be used as a tool to affect the humans’ sleep-awake rhythm. With the new paradigm shift with LED and OLED comes an opportunity to change the colour temperature of the lighting and use blue-enriched light as a tool to possibly create a better working environment for shift working truck drivers using warmer light at night and colder light in the morning.
In this thesis two main studies has been conducted, the first was regarding product and user knowledge and the second was a lighting study. From these studies we have concluded three analyses and suggested a lighting planning guide for Scania that takes into account future lighting planning with new technology for a better working environment for long-haulage truck drivers.
Terminology
Some useful terms for this thesis are explained in this chapter. Accommodation – The lens adjustment of focal lengthCandela – The SI-unit for luminous intensity (cd)
Circadian rhythm – Processen in biological organism with the duration of approximately for 24 hours
Colour rendering - Effect of an illuminant on the colour appearance of objects by conscious or subconscious comparison with their colour appearance under a reference illuminant
Colour rendering index (CRI) - CRI is a quantitative measure of the ability of a light source to reveal the colours of various objects faithfully in comparison with an ideal or natural light source (Unit=Ra)
Direct lighting – The light source illuminates the motive directly Directional lighting – Lighting directed in a certain direction Disability glare – Disability glare impairs the vision of objects
Discomfort glare – Instinctive desire to look away from a bright light or making it difficult to perform a task
Flicker – Visible quick changes in luminious intensity Glare – Difficulty seeing due to bright light
Illuminance (at a point of a surface) Incandescent (electric) lamp - Glödlampa
Indirect lighting – Lighting not directed towards the motive
Luminous flux – Amount of light from a light source. Unit: Lumen (lm) Luminous intensity – Amount of light in a given direction (cd)
Monochromatic light – Light exhibiting one colour
Polychromatic light – Light exhibiting more than one colour Reflectance – A surface effectiveness in reflecting radiant energy
Table of content
1 INTRODUCTION ... 1
1.1 SCANIA CVAB ... 1
1.2 DEPARTMENT OF PHYSICAL VEHICLE ERGONOMICS (RCDE) ... 1
1.3 LONG-HAULAGE TRUCK ... 1
1.4 PROBLEMATIZATION ... 2 1.5 PURPOSE ... 3 1.6 OBJECTIVE ... 3 1.7 RESEARCH QUESTIONS ... 3 1.8 APPROACH ... 3 1.9 LITERATURE ... 3 1.10 DELIMITATIONS ... 4 2 THEORETICAL FRAMEWORK ... 5 2.1 VISUAL ERGONOMICS ... 5 2.2 LIGHT ... 9 2.3 LIGHTING TECHNOLOGY ... 16 2.4 LIGHTING PLANNING ... 19
2.5 PRODUCT DEVELOPMENT PROCESS ... 22
2.6 DRIVING AND REST PERIODS FOR TRUCK DRIVERS ... 24
3 METHODOLOGY ... 27
3.1 PRODUCT AND USER KNOWLEDGE ... 28
3.2 LIGHTING STUDY ... 31
3.3 LIGHTING PLANNING IN A TRUCK CAB ... 34
4 EMPIRICAL FINDINGS ... 35
4.1 EMPATHY STUDY ... 35
4.2 BENCHMARKING ... 37
4.3 INTERVIEW AND DATA GATHERING... 38
4.4 FLEXIBLE MODELLING ... 41
5 ANALYSIS 1- TRUCK COMPACT LIVING ... 46
5.1 THE DRIVER ... 46
5.2 CURRENT LIGHTING ... 46
5.3 CONCLUSION –TRUCK COMPACT LIVING ... 48
5.4 DISCUSSION –TRUCK COMPACT LIVING ... 48
6 ANALYSIS 2 – NEW TECHNOLOGY FOR A BETTER WORKING ENVIRONMENT ... 49
6.1 LIGHTING PLANNING WITH LED AND OLED ... 49
6.2 ASPECTS OF LIGHT ... 50
6.3 MEASURING LIGHT ... 57
6.4 DAYLIGHT AND BLUE ENRICHED LIGHT ... 58
6.5 COLOUR TEMPERATURE AND RENDERING ... 59
6.6 CONCLUSION –NEW TECHNOLOGIES FOR A BETTER WORKING ENVIRONMENT ... 59
6.7 DISCUSSION –NEW TECHNOLOGIES FOR A BETTER WORKING ENVIRONMENT ... 60
7 ANALYSIS 3 – LIGHTING PLANNING IN A TRUCK CAB... 62
7.1 LIGHTING PLANNING AND PRODUCT DEVELOPMENT ... 62
7.2 PLANNING FOR FLEXIBILITY ... 62
7.3 CONCLUSION –LIGHTING PLANNING IN A TRUCK CAB ... 63
7.4 DISCUSSION –LIGHTING PLANNING IN A TRUCK CAB... 63
8.1 OVERALL ANALYSIS ... 64
9 INTERIOR LIGHTING PLANNING GUIDE ... 65
9.1 IDENTIFY CUSTOMER NEEDS ... 68
9.2 TRANSLATE CUSTOMER NEEDS ... 68
9.3 IDENTIFY DOMAIN REQUIREMENTS ... 68
9.4 ANALYSE ... 68
9.5 ESTABLISH TARGET SPECIFICATION ... 69
9.6 GENERATE LIGHTING CONCEPTS ... 69
9.7 EVALUATE LIGHTING CONCEPTS ... 70
9.8 CONTROL FINAL CONCEPT ... 70
9.9 FURTHER STUDIES ... 70
9.10 DISCUSSION OF WORKING METHODOLOGY ... 71
10 REFERENCES ... 73
11 APPENDIX 1 - EMPATHY STUDY ... 77
12 APPENDIX 2 – BENCHMARK ... 80
13 APPENDIX 3 - INTERVIEW QUESTIONS ... 85
13.1 OPENING QUESTIONS (5 MIN) ... 85
13.2 AN ORDINARY DAY (15 MIN) ... 85
13.3 THE TRUCK CAB (10 MIN) ... 85
13.4 LIGHTING (15 MIN) ... 86
13.5 FINAL QUESTION (5 MIN) ... 86
14 APPENDIX 4 - PERSONAS... 87
15 APPENDIX 5 – PROTOTYPING ... 94
16 APPENDIX 6 - FLEXIBLE MODELLING... 95
17 APPENDIX 7 - QUESTIONNAIRE ... 101
List of figures
FIGURE 1-1, ONE OF SCANIA’S LONG-HAULAGE TRUCKS AND ONE OF THE AUTHORS. ... 2 FIGURE 2-1, LIGHT WITHIN THE VISIBLE SPECTRA IS DETECTED BY THE EYE WHICH HELPS US FORM COLOURED
IMAGES (ADOPTED FROM RENSTRÖM &HÅKANSSON,2013 P.11 AND NYLÉN,2012 P.17). ... 6
FIGURE 2-2, PHYSICAL UNITS OF LIGHT (INSPIRED FROM P.22(RENSTRÖM &HÅKANSSON,2013) AND
(STARBY,2003)) ... 10 FIGURE 2-3, THE LIGHT DISTRIBUTION CURVE SHOWS HOW LIGHT IS DISTRIBUTED FROM A LAMP OR A FIXTURE
(INSPIRED BY (RENSTRÖM &HÅKANSSON,2013)). ... 11 FIGURE 2-4, THE RULE OF DISTANCE EXPLAINS HOW MUCH A SURFACE AT A DISTANCE FROM A LIGHT SOURCE
IS ILLUMINATED (INSPIRED BY (STARBY,2003)). ... 13 FIGURE 2-5, PRINCIPLE SKETCH OF DESIRABLE RATIO,5:3:1, CENTRAL: NEAR PERIPHERAL: FAR PERIPHERAL,
BETWEEN LUMINANCE IN THE VIEWING FIELD (INSPIRED BY (NYLÉN,2012)). ... 14 FIGURE 2-6, THE ANGLE BETWEEN ANY LIGHT SOURCE AND THE DIRECTION OF VIEW SHOULD AT LEAST BE 45
DEGREES TO AVOID DIRECT GLARE (INSPIRED FROM BOHGARD, ET AL.(2010)). ... 16 FIGURE 2-7, THE CUT-OFF ANGLE AND SHIELDING ANGLE ARE USED TO SHIELD A LIGHT SOURCE FROM GLARE
(INSPIRED FROM LJUSKULTUR (2013)). ... 16 FIGURE 2-8, THE LIGHTING PLANNING PROCESS ACCORDING TO LJUSKULTUR (2013). ... 20
FIGURE 2-9, CONCEPT DEVELOPMENT PROCESS DEVELOPED BY ULRICH &EPPINGER (2008). ... 23 FIGURE 2-10, EXAMPLES OF TRUCK DRIVER SCHEDULES (INSPIRED BY THE REGULATIONS ON
TRANSPORTSTYRELSEN (2015)). ... 26 FIGURE 3-1, THE WORK PROCESS OF THE THESIS. ... 27 FIGURE 3-2, A CAPTURE FROM DIAUX EVO6.0 SOFTWARE OF AN APPROXIMATE RE-CREATION OF A LONG
-HAULAGE TRUCK CAB. ... 34
FIGURE 4-1, LIGHTS FROM STORAGE SPACES CAN HAVE A GLARING EFFECT. ... 37 FIGURE 4-2, RESPONSE RESULTS FROM QUESTIONNAIRE.EACH PARTICIPANT ASSERTED A VALUE FROM 1-6 TO EACH STATEMENT WHERE 1 CORRESPONDS TO “NOT AGREEING AT ALL WITH THE STATEMENT” AND 6
TO “COMPLETELY AGREE WITH THE STATEMENT”. ... 43 FIGURE 4-3, RELATIVE SCORE FOR EACH CORRELATED STATEMENT.EACH SCORE SUGGESTS THEIR RELATIVE
IMPORTANCE ACCORDING TO PARTICIPANTS’ ANSWERS. ... 44 FIGURE 5-1, PLACEMENT AND INTENSITY OF LIGHT SOURCES IN TRUCK CAB. ... 47 FIGURE 5-2, NEED OF LIGHT IS CRITICAL IN TIGHT SPACES ESPECIALLY AROUND THE INSTRUMENT PANEL
WHERE YOU WOULD NEED LIGHT TO FIND STORED ITEMS. ... 47 FIGURE 5-3, UTILIZING THE FLEXIBILITY OF THE READING LAMPS CAN CREATE INDIRECT LIGHT AND CAUSE
DEPTH AND CHARACTER TO THE INTERIOR ENVIRONMENT OF THE TRUCK CAB. ... 48 FIGURE 6-1, AN INSTALLATION OF LED STRIPS ILLUSTRATING AN OLED INSTALLATION WAS USED FOR
FLEXIBLE MODELLING. ... 50
FIGURE 6-2,AN EXAMPLE OF AN ANALYSIS OF LIGHT DISTRIBUTION IN DIALUX EVO 6.0. ... 51 FIGURE 6-3, MONOCHROMATIC RED LIGHT IS OFTEN USED FOR AMBIENT LIGHT WHILE DRIVING AT NIGHT TO
GET A GENERAL PERCEPTION OF THE TRUCK CAB. ... 52 FIGURE 6-4, ANGLE AND DISTANCE BETWEEN LIGHTED OBJECT AND LIGHT SOURCE, AND LUMINOUS FLUX ARE
CRITICAL WHEN SHADOWS ARE GENERATED. ... 54 FIGURE 6-5, A HUMANS FIELD OF VIEW IN A TRUCK CAB.THE ILLUSTRATION IS NOT AN EXACT
REPRESENTATION OF A REAL LIFE SETTING. ... 55 FIGURE 6-6, A TYPICAL SCENARIO WHERE DIFFERENCES IN CONTRAST WOULD OCCUR... 55 FIGURE 6-7, DIFFERENCES IN CONTRAST WILL OCCUR IN THE TRUCK CAB, AND IT IS IMPORTANT TO ADDRESS
THESE ISSUES AND TO AVOID THEM IN TYPICAL USER SCENARIOS, E.G. LOOKING AT A BRIGHT SCREEN. 56 FIGURE 6-8, LIGHT SOURCES AND THEIR POWER DISTRIBUTION, COLOUR TEMPERATURE AND THEIR EFFECT ON MELATONIN SUPRESSION (INSPIRED FROM AN ARTICLE ABOUT OLED AND ITS POTENTIAL FOR HEALTHY LIGHT AT NIGHT TIME (JWO-HUEI &CHUN-YU,2013).THE ORIGINAL FIGURE IS A COMPLIATION OF STUDIES). ... 58 FIGURE 6-9, A SCHEMATIC REPRESENTATION OF A HYPOTHETICAL RELATION BETWEEN DRIVER ALERTNESS AND THE PRESENCE OF THE SUN IN SWEDEN DURING THE WINTER SEASON. ... 60
FIGURE 17-1, QUESTIONNAIRE FROM THE FLEXIBLE MODELLING WORKSHOP. ... 101 FIGURE 18-1,VISUAL/PHYSICAL CONDITIONS INSPIRED BY (LJUSKULTUR,2013) ... 102
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1 Introduction
This chapter explains the problematization, purpose and research questions in this thesis. The objective of the thesis will be achieved by literature study and through gained knowledge of the product and the user. The delimitations of the thesis are also explained.
1.1 Scania CV AB
Scania CV AB, hereafter called Scania, is a company with sales and service organisation in more than 100 countries and with its production in Europe and Latin America. The Head Office and research and development operations is located in Södertälje, Sweden. In total approximately 42000 employees work at Scania and out of these about 3500 work with research and development. (Scania, 2013)
The company’s objective is to provide the best profitability for its customers throughout the product life cycle by delivering optimised heavy trucks and buses, engines and services. All off Scania’s operations are based on the company’s core values; customer first, respect for the individual, and quality and is applied as a unified concept. (Scania, 2013)
1.2 Department of Physical Vehicle
Ergonomics (RCDE)
This thesis was written at the department of physical vehicle ergonomics at Scania in Södertälje.
1.3 Long-haulage truck
The long-haulage truck (see Figure 1-1) is used to move different types of cargo, often long distances which can take several days. This is why long-haulage trucks often are equipped for compact living inside the truck cab. The
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truck cab is an environment where the truck driver both works, rests and sleeps.
Figure 1-1, one of Scania’s long-haulage trucks and one of the authors.
1.4 Problematization
Light affects our senses every day, from the moment we wake up we experience countless sets of lightings. Every individual perceive the element of light different, in the way that the eye physically reacts and how it consequently affects the psychological and physical well-being of the human body. Light is also what creates visual experiences for indoor and outdoor environments.
The way light affect the human is an important factor in the everyday work of many. Several big companies use some set of requirements regarding ergonomics, where physical load on the human body is in focus. It is important to provide employees with a safe and ergonomic work environment but also a satisfying environment to maintain efficiency and to empower their will to work. For many truck drivers the majority of the time spend is often limited to the inside of the truck cab and is therefore also a place for resting and living. The cab is provided with equipment for, e.g., cooking and sleeping and one might consider it a minimalistic and compact living. With the truck driver’s well-being in mind it is important as a cab designer to help facilitate low physical and psychological load in every sense possible. The truck driver experience several sources of light during working hours and it is therefore in the users and the company's interest to create the best lighting possible.
Incandescent lights is common in over-head installations in e.g. long-haulage trucks or cars. The LED technology is rapidly gaining foothold in interior
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lighting and many preferred qualities can be extracted from that. In Scania's interest, LED along with newer technology is the future of interior lighting both from an economic and also competitive perspective.
1.5 Purpose
The purpose of this study is to explore the needs and opportunities to improve the working environment in a truck cab with lighting design when planning for interior lighting in a truck cab by using LED (Light Emitting Diode) and/or OLED (Organic Light Emitting Diode) and how it could affect the working environment for truck drivers.
1.6 Objective
The objective with this study is to create a planning guide plan for lighting design in a truck cab.
1.7 Research questions
The research questions that will be answered in this study are:
Is there a need for personalized lighting in a truck cab?
How can lighting planning and LED/and or OLED improve the lighting environment in a truck cab?
1.8 Approach
The approach for this study is to gain knowledge in the subject of visual ergonomics and lighting design by studying literature, interview experts in visual ergonomics and lighting design. Knowledge about the user, truck drivers, and the product, the truck cab, will be gained with a user study and benchmark of existing interior lighting in long haulage trucks. The knowledge is supposed to aid in further development and research in the area studied.
1.9 Literature
The base of the literature study shall include studies and reports regarding visual ergonomics, the technology of LED (Light Emitting Diode) and OLED (Organic Light Emitting Diode), also traditional lighting planning. The
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literature will be used as a tool to build knowledge and to bring substance to the research and to aid in answering the research questions.
1.10
Delimitations
The following delimitation will be made in the study:
Production - The conclusions of this thesis will not consider production nor construction of light installations.
Financial - The conclusions of this thesis will not consider financial aspects of new technology or light installations.
Only interior lighting - The thesis covers only the interior lighting inside the cab of a truck. Furthermore, light from indication lights or instrument panel will not be regarded.
2 Theoretical framework
This chapter contains the theoretical framework of this study. The theoretical framework is divided into six sections; Visual ergonomics, Light, Technology, Lighting planning, Product development process and Driving and rest periods for truck drivers.
2.1 Visual ergonomics
Visual ergonomics is the knowledge about how our eyes and vision is affected of the things we see and its consequences on our health and performance (Renström & Håkansson, 2013). According to International Ergonomics Association (IEA, u.d.) the definition of visual ergonomics is as following:
"Visual ergonomics is the multidisciplinary science concerned with understanding human visual processes and the interactions between humans and other elements of a system.
Visual ergonomics applies theories, knowledge and methods to the design and assessment of systems, optimizing human well-being and overall system performance. Relevant topics
include, among others: the visual environment, such as lighting; visually demanding work and other tasks; visual function and performance; visual comfort and safety; optical
corrections and other assistive tools."
Within visual ergonomics there are four main subjects, the vision, the lighting, the work piece and the impact from the surroundings (Nylén, 2012). Many benefits can be found with successful visual ergonomics in a working environment, both for the employer and the employee. It doesn´t take a lot of effort or investment to create a good visual environment. With only common sense and know-how, problems as being blinded by lighting, contrast between working pieces and the background, and also sufficient lighting in a workspace can be corrected. Good visual ergonomics can be achieved with correct directional lighting, no blinding lights, good colouring and evenly distributed light (Renström & Håkansson, 2013). Important parameters when processing light are; contrast, colour- and night vision, depth perception and detection of movement (Bohgard, et al., 2010).
2.1.1 The Eye
The knowledge about the human eye’s function and its anatomy is of interest when trying to understand how lighting in a working environment affects the user and how the lighting should be designed (Nylén, 2012).
Out of all our senses, sight has the most impression on our brain with 80% of the total impression from our senses (Nylén, 2012). The eye detects the visual light of the spectra (see Figure 2-1). Humans rely mostly on the visual sense and is very effective to see movement (Bohgard, et al., 2010). The visual sense is actively looking for pattern and structures.
The first thing the light hits is the cornea where most of the focusing is done (Nylén, 2012). The refractions in the cornea is 2/3 of the total refraction in the eye (Hemphälä, 2008). After the light has passed the cornea the lens refracts the remaining 1/3 and the light travels through the vitreous and hits the retina. In the retina there are two kinds of photoreceptors, cones and rods that transform the light energy into nerve signals that through nerve cells ends up in the brain. The rods detects all kinds of light no matter the colour of the light (Nylén, 2012). They are more sensitive to light than the cones and signals only in a grayscale from black to white. At dusk, when there is not much light, only the rods gives signals to the brain. Also the rods are few in the central part of the field of view, which makes the night vision less detailed as in an environment with daylight. In the retina there are 10 billion photoreceptors, but the distribution of photoreceptors is uneven. Only in a little region of between 1-2% is the vision sharpest. In this region the vision is roughly similar as the resolution of a 200-500 megapixel camera. The amount of light that is projected onto the retina is adjusted with the pupil (Renström & Håkansson, 2013).
Figure 2-1, light within the visible spectra is detected by the eye which helps us form coloured images (adopted from Renström & Håkansson, 2013 p.11 and Nylén, 2012
p.17).
The eyes ability to adjust the focus on objects in different distances to the eye is called accommodation (Renström & Håkansson, 2013). A transition in the size of the lens occurs instantly when the lens changes its elasticity on the inside and outside. An object that is closer to the eye needs more convergence than an object that is further away (Nylén, 2012).
2.1.2 Circadian system
The human among many living organisms possess the ability to adapt to phase shifting light conditions, meaning our biological clock is mainly steered by the presence and absence of sunlight. The biological phenomena is called the circadian clock which refers to the internal timing of a 24 h rhythm, which would refer to a "daily rhythm" in common language. The circadian clock is the reason for shifting between sleep and alertness. (Fuhr, et al., 2015)
Several studies has been made about the issues with altering the circadian rhythm and how it affects us (Boyce & Hopwood, 2013) (Cajochen, 2007) (Holzman, 2011) (Kramer & Martha, 2013) (LeGates, et al., 2014), this thesis include a handful of these studies. Changes in routines can influence our sleep and consequently change our mood and cognitive function negatively, this is agreed by most without an exact reference. The idea of the connection between light and the circadian clock would explain why e.g. shift workers experience negative physical and cognitive effects due to shifting lighting environment. Disturbance of circadian rhythm is closely connected to depression and effects from light therapy have been detected as a positive factor regarding e.g. sleep deprivation or seasonal affective disorder (Boyce & Hopwood, 2013).
2.1.3 Non-visual effects
The eye and the retina not only helps us form images but work as a detector of light which consequently regulates numerous behavioural and physiological functions. This group of functions is called non-image-forming visual functions (NIF visual functions). These NIF visual functions are major contributors of the regulation of the circadian clock where the periodical changes in light confine our activity-rest rhythm (LeGates, et al., 2014). When the retina of the eye is exposed to certain wavelengths of bright light, melatonin secretion is suppressed (Boyce & Hopwood, 2013). Melatonin is a hormone and should peak in level during night when we should be the most tired. Beside this, light might affect humans independently of the circadian rhythm, basically meaning that the eye responses to light during exposure and stops responding after exposure. In order to alter the attention, alertness and emotional processes, short wavelengths of blue light are preferred (LeGates, et al., 2014).
Studies in the past decades show that light has a strong influence on a human’s state of alertness from the brain’s non-visual detection of light (Cajochen, 2007). Blue light at a certain wavelength suppresses the melatonin secretion causing us to think that we should be awake, due to alertness and the circadian rhythm. Most of us are frequently subjected to blue light at night when we are using our computers, TVs, tablets or smartphones. Blue light affects our biological clock most negatively at night, and at the same time affects us in the most positive way during the day, it keeps us alert (Holzman, 2011).
Cajochen (2007) stresses the importance of reliability of test results on suppression of melatonin secretion and the importance of the difference between laboratory testing and a real life setting. To measure alertness one
might, according to Cajochen (2007) use subjective or objective ratings where subjective ratings may be misleading due to intuitive answers from test subjects. To measure alertness or fatigue on a test subject in a real life setting, e.g. truck driving, the nature of interference needs to be taken into account. Electroencephalographic (EEG) and electrooculography (EOG) monitoring will measure brain activity and eye movement. Such measures can be used to verify levels of alertness or fatigue while their nature of interaction is a big disadvantage.
Cajochen (2007) also mentions that past research mainly uses bright light (>1000 lux) while a normal lighting in a room is about 100-200 lux. However, Kozaki, et al. (2008) made a study on the suppression of melatonin secretion with illuminance (the amount of light) of 200 lux, which was meant to simulate a normal indoor environment. The result show that light at 5000K supress melatonin secretion considerably more than for light at 3000K. The result conform to at least three studies that has been done on suppression of melatonin secretion from light (Kozaki, et al., 2008).
Kuijsters, et al. (2015) made a study on elderly people where they exposed them to two sets of lighting in a closed environment. It is shown that light in a closed environment can create a cosy and an activating environment that affects elderly people in a state of an anxious or a sad mood. The study shows that a whiter and “active” environment will affect people in a sad mood positively and that a warmer and cosy environment will affect people in an anxious mood positively.
2.1.4 Sight changes with aging
Our sight changes with aging and it gets tougher to handle different visual tasks as we get older (Bohgard, et al., 2010). By the age of 40-50 years old it is noticeable that the lens in the eye gets stiffer and can’t go back to its spherical shape as in a younger age. The term for this phenomenon is presbyopia.
The eyes ability to accommodate reduces with aging and it gets more difficult to get a clear view since the depth of focus reduces and the accommodation takes longer (Bohgard, et al., 2010). Increasing age means increased need of light significantly (Nylén, 2012). The author further explains that a 50-year old person needs 200% and a 60-year old 300% more than a 20-year old.
2.1.5 Sleeping disorders and shift working truck drivers
In 2013, SBU released a report about the correlation between the working environments and sleeping disorders (SBU - Swedish Council on Health Technology Assessment, 2013). One who suffers from disrupted sleep may encounter issues such as low energy during the day, mood swings and decreased concentration. A survey from 2008 with 1 550 Swedish participants 18 to 84 years old showed that roughly one in four experience some sort of sleeping disorder. One of many reasons, regarding sleep, for a Swedish worker to be negatively affected by work is to be thinking about work duringfree-time. From SBU’s report one in five from a study in 2011 indicated problems with sleeping due to this.
In 2002, VTI (Swedish institute for research of road and transport) made a police-report summary of road accidents caused by tiredness (Larsson & Anund, 2002). It is discussed that sleepiness behind the wheel contributes to 10-20% of all traffic accidents. The report shows that for tiredness, single-vehicle accidents at 90-110 km/h is the dominating relation, meaning it is likely to be on the highway.
In 2015 Pylkkönen, et al. made a study about sleepiness and sleep for shift-working long-haul truck driver’s methods they used for counter measuring sleepiness. The study containing 54 long-haul truck drivers with at least 2 years corresponding work experience was conducted in Finland during the winter months from November to March. With four different shift-types studied the conclusion was that sleepiness and severe sleepiness at the wheel is widely common for shift working long-haul truck drivers. Depending on the type of shift different sleepiness countermeasures was used, such as intake of caffeine, taking a nap, having a light or heavy meal, smoke or take a walk outdoors (Pylkkönen, et al., 2015).
2.2 Light
Light is what we call the electromagnetic radiation that we can perceive when it hits our retina (Nylén, 2012). The human visual system reacts to wavelengths in the span of 380-780 nanometres (nm) (Boyce, 2014). Other creatures reacts to different spans of wavelengths. The different wavelengths for different colours of light are approximately for blue 430-500 nm, green 515-560 nm, yellow 565-585 nm and red 600-780 nm (Nylén, 2012). When we talk about light we usually refer to luminous flux, luminous intensity, illuminance and luminance (see Figure 2-2).
Figure 2-2, physical units of light (inspired from p.22 (Renström & Håkansson, 2013) and (Starby, 2003))
2.2.1 Luminous environment
The meaning of the term luminous environment is such which is affected of sources of light and their characteristics, the lights spectral composition and direction, how much light that hits different objects and the objects reflection. Not only is good lighting a presumption to get correct information, but has a esthetical dimension which can affect our well-being. Variations in lighting has an effect on biochemical processes in the body such as seasonal changes and variations during the day affects our circadian rhythms. (Bohgard, et al., 2010)
2.2.2 Luminous flux
Luminous flux is the term for the amount of light a light source emits. The unit for Luminous flux is lumen (Lm). Both the luminous flux and the lighting fixture is crucial to achieve the desired illuminance. (Renström & Håkansson, 2013)
2.2.3 Luminous intensity
Luminous intensity is a term for the intensity of the luminous flux in a certain direction (Renström & Håkansson, 2013). The unit for Luminous intensity is Candela (cd). Luminous intensity is displayed in a light distribution curve, which shows how the light varies around the fixture, see Figure 2-3. The graph represent a cross section of a lamp or fixture’s luminous intensity in every angle. If the curve reaches above the horizontal centreline it indicates that light is distributed above the fixture. As for the picture on the left the luminous intensity is approximately 680 candela [cd] and is only distributed
downwards. The light distribution curve ease the planning of a new lighting project (Renström & Håkansson, 2013).
Figure 2-3, the light distribution curve shows how light is distributed from a lamp or a fixture (inspired by (Renström & Håkansson, 2013)).
2.2.4 Illuminance
Illuminance is the term for the amount of flux that strikes a surface (Renström & Håkansson, 2013). The unit for illuminance is Lux (lx) and 1 Lux is when a luminous flux of 1 lumen illuminates evenly an area of 1 m2. Different types of work require different amount of illuminance (Nylén, 2012). Illuminance is not a measurement of lighting quality, which is often misinterpreted, since it doesn’t describes the experience of the lighting environment. Illuminance is measured with a lux-meter (Renström & Håkansson, 2013).
2.2.5 Luminance
Luminance is the term for the amount of luminous flux reflected on a surface (Renström & Håkansson, 2013). The unit for luminance is candela per m2 (cd/m2). Two surfaces with the same amount of illuminance can differ in the amount of luminance, depending on their reflectance (Nylén, 2012). A dark surface has less reflectance than a white surface. The visual experience between the dark surface and the white is called brightness difference and what is measured is called luminous difference (Renström & Håkansson, 2013). It is important to consider recommended limits of luminance, when planning new lighting, but it doesn't ensure a good visual experience (Renström & Håkansson, 2013). The perception of luminance differs among people due to how well the eye is adjusted to light (Nylén, 2012). A general recommendation of comfort reasons is not levels over 2000 cd/m2 and definitely not levels over 10000 cd/m2. Luminance at this level can do damage to the retina. Other symptoms caused of the experience of great luminance differences are stress, tiredness and glare (Renström & Håkansson, 2013). The luminance level of some none-covered fluorescent lighting is sometimes over
10000 cd/m2 and therefore needs to be foreclosed or not appear in the viewing field (Nylén, 2012).
Luminance is measured by a luminous meter which is pointed to a surface like a camera. It is quite complicated but important knowledge can be gained. (Renström & Håkansson, 2013)
2.2.6 Colour temperature
Objects only have an ability to reflect colours from the light spectra that is why it is so important to choose the right light source to accentuate the visual expression of an object or environment. Regarding artificial light, colour temperature and colour rendering index are the factors that separate one light source from another. Colour temperature is measured in Kelvin (K) and is often divided into warm (yellow) and cold (blue). (Wall, 2009)
The character of the lighting are described as the apparent colour of the light and is also called chromaticity. The correlation between the colour characteristics and the colour temperature of the artificial light (Tcp), can be seen below in Table 2-1. Daylight is always changing its intensity and colour temperature. Research shows that lighting not only have a visual impact on humans, but also a biological and emotional impact. (Ljuskultur, 2013)
Table 2-1, a description of relation between how colour often is perceived in terms of temperature (inspired by (Ljuskultur, 2013)).
It is a balance of psychology, aesthetics and the perception of what’s natural when deciding the colour temperature of lighting. Colder light is often preferred in warmer climate and warmer lighting in colder climate (Ljuskultur, 2013). Basically, a regular 60 W light bulb has the colour
Colour characteristics Correlated colour temperature Tcp
Warm Below 3300K
Neutral 3300-5300K
temperature 2700K, a cloudy sky 6500K and a blue sky 30 000K (Bohgard, et al., 2010).
2.2.7 Colour rendering index
The quality of colour rendering of a light source is expressed in colour rendering index (CRI), or also called Ra-index. Maximum value is 100 and comes from an ideal light source. A light source has excellent colour rendering if the Ra-value is above 90, good colour rendering above 80 and poor colour rendering if below 80. (Renström & Håkansson, 2013)
2.2.8 Rule of distance
When a light source is active and cause illuminance upon a surface perpendicular to the beam, the distance between the light source and surface cause different illumination. The rule (see Figure 2-4) says that the illumination changes due to changes of the square value of the distance (Starby, 2003).
Figure 2-4, the rule of distance explains how much a surface at a distance from a light source is illuminated (inspired by (Starby, 2003)).
2.2.9 Light source efficiency
When comparing light sources it is common to refer to the light source efficiency -how much luminous flux (lumen) a light source emits relative its electrical power. This relation is expressed as lumen per watt (Lm/W). For a retailer of lamps it is most usual to express this specifically for the lamp, but in fact there may be a loss in effect due to different light fixtures. E.g. if a retailer sells a 36W light bulb that emits 3000 Lm the light efficiency is told to be 3024/36= 84 Lm/W, but if the loss from the fixture is 10W the efficiency is 3024/(36+10)=65,7 Lm/W. So the lighting designer should consider the so called system effect of the lamp. (Starby, 2003)
2.2.10
Shadows and Contrasts
Shadows makes it easier to estimate distances and to perceive shapes. Objects appearances change depending on the direction from which the light comes from. Directed light results in sharper shadows and light from several different light sources makes the light and the shadows soft. (Renström & Håkansson, 2013)
Contrast is perceivable differences in colour and brightness (Renström & Håkansson, 2013). Being blinded due to contrast of two adjacent surfaces with great difference in brightness can cause blinding and is called contrast blinding (Nylén, 2012). Preferably should the distribution of the luminance in the central part, the adjacent and the peripheral parts be in the ratio 5:3:1, see Figure 2-5. Contrast blinding occur when the difference of luminance is greater than 100 times as much as the other, but many factors affects contrast glare as distance between the surfaces and their sizes. To be able to see clearly the contrast need to be well balanced (Renström & Håkansson, 2013). Also factors such as genetics and age correlates to the perception of contrast blinding (Nylén, 2012).
Figure 2-5, principle sketch of desirable ratio, 5:3:1, central: near peripheral: far peripheral, between luminance in the viewing field (inspired by (Nylén, 2012)).
2.2.11
Reflectance
Reflectance is the term of the amount light a surface can reflect. A surface reflectance property is defined in percentage. As example, a black matte
surface reflects 5% of the incoming luminous flux whereas a white matte ceiling often reflect more than 85% of the incoming luminous flux. (Renström & Håkansson, 2013)
2.2.12
Glare
Glare occurs when the eye is exposed to brighter light than what the eye is adapted to (Ljuskultur, 2013). Also bright surfaces or intense reflection can have a glaring effect. Older people have more difficulty in adapting to different luminous environments and therefore get easier blinded by light. Glare can be prevented by shielding the light source and correct placement (Renström & Håkansson, 2013).
To quantify glare it is proper to use a luminance meter to assess the amount of discomfort blinding lights by using the UGR method (Unified Glare Rating). The UGR method is based upon a formula developed by the international commission on illumination. UGR refers to the measure of emitting luminance from a fixture to the eye when the eye has a fixed line of sight. How to measure UGR can also be seen in SS-EN 12464-1. According to Ljuskultur (2013) the formula is as follows: 𝑈𝐺𝑅 = 8𝑙𝑜𝑔10( 0.25 𝐿𝑏 ∑𝐿 2𝜔 𝑝2 ) 𝐿𝑏 = 𝐿𝑢𝑚𝑖𝑛𝑎𝑛𝑐𝑒 𝑖𝑛 𝑡ℎ𝑒 𝑏𝑎𝑐𝑘𝑔𝑟𝑜𝑢𝑛𝑑 (𝑐𝑑 ∗ 𝑚2) 𝐿 = 𝐿𝑢𝑚𝑖𝑛𝑎𝑛𝑐𝑒 𝑎𝑡 𝑡ℎ𝑒 𝑏𝑟𝑖𝑔ℎ𝑡 𝑠𝑝𝑜𝑡𝑠 𝑎𝑡 𝑒𝑎𝑐ℎ 𝑙𝑖𝑔ℎ𝑡𝑖𝑛𝑔 𝑓𝑖𝑥𝑡𝑢𝑟𝑒 𝑖𝑛 𝑡ℎ𝑒 𝑑𝑖𝑟𝑒𝑐𝑡𝑖𝑜𝑛 𝑜𝑓 𝑡ℎ𝑒 𝑣𝑖𝑒𝑤𝑒𝑟𝑠 𝑒𝑦𝑒.
𝜔 =Angle between the direction of sight and the centre of each light source. 𝑝 = 𝐺𝑢𝑡ℎ𝑠 𝑝𝑜𝑠𝑖𝑡𝑖𝑜𝑛 𝑖𝑛𝑑𝑒𝑥
Four different types of blinding lights can be avoided due to a well-planned lighting- and workplace design according to (Bohgard, et al., 2010):
1. Direct glare, due to blinding lights hitting the eye directly. 2. Indirect glare, due to reflection in reflecting materials.
3. Contrast glare - Being blinded due to great difference of luminance in the viewing field.
4. Adaption glare - Being blinded due to quick changes between a bright and dark environment.
To avoid being directly blinded from a light source, should it be placed with at least 45° angle from the direction of the view, see Figure 2-6.
Figure 2-6, the angle between any light source and the direction of view should at least be 45 degrees to avoid direct glare (inspired from Bohgard, et al. (2010)).
Direct light from light sources can cause disability glare and if so should be shielded (Ljuskultur, 2013). The shielding angle is the angle between the horizontal line and the first line of sight where a light source can be seen, see Figure 2-7. The cut-off angle is the angle is from the vertical line and to the line where light from light sources or surfaces with high luminance is longer visible.
Figure 2-7, the cut-off angle and shielding angle are used to shield a light source from glare (inspired from Ljuskultur (2013)).
2.3 Lighting technology
In this chapter follows a brief descriptions of LED, what to think of when dimming LED and also OLED.
2.3.1 LED
Light emitting diode (LED) is a semiconductor activated by electrical current and emits light of different colours through electrical stimulation (Renström & Håkansson, 2013). LEDs differ from traditional light sources where emitting light is a secondary product from a heat source often mixed with gas. LED-technology has now progressed to compete and go beyond conventional light sources in matter of light output and colour characteristics (Khanna, 2014).
A LED doesn’t emit UV- nor IR- radiation and are therefore suitable for sensitive environments (Renström & Håkansson, 2013). The LED lights up instantly when activated by electrical current and has extremely high luminous flux. It hasn’t any sensitive parts and can therefore bare vibrations and mechanical stress. LED-lights can easily cause glare and needs to be combined with various forms of reflectors, optics or some diffusing material. LED technology changes traditional lighting standards and housings and conventional thinking is not applicable to this technology (Khanna, 2014). One factor that defines the quality of LED-lights is that the colour temperature doesn’t change over time. White light from LEDs are blue LEDs with a layer of phosphorus on top. The phosphorus layer creates yellow light which combined with the blue light results in white light. The CRI-index for LED-lights can vary from 60 to 95 (Renström & Håkansson, 2013).
The characteristics of a LED is mostly its ability to control the light spectra and to direct light without having to use reflectors where light often is trapped in the fixture (Renström & Håkansson, 2013).
2.3.2 Dimming LED
Flicker is the term for quick luminous variations which can be perceived and is subjective. The physiological term, when the frequency of the flicker is greater than we can perceive, is amplitude modulated light variations. The impact amplitude modulated light has on people varies from no problems to, migraine, unconsciousness and epileptic seizures (Hemphälä & Nylén, 2013). Both flicker and amplitude modulated light variations should be avoided (Belysningsbranschens Tekniska Komitté, 2015).
There are two main types of techniques for regulating the luminous intensity in actuators for LED-lighting according to Belysningsbranschens Tekniska Komitté (2015):
Pulse Width Modulation (PWM), is an actuator with a modified voltage. The frequency shouldn’t be below 300 Hz, due to eventual risk of flicker. A High-quality actuator with PWMs shouldn’t flicker, but low-High-quality actuators might when not applying the existing recommendations. Many actuators combines PWM with amplitude modulation at low luminous intensity levels.
Amplitude Modulation (AM), is a technique which means current reduction to reduce the luminous intensity and can’t cause flicker.
A concern from the lighting industry is that flicker from magnetic-ballasted fluorescent, metal balide and high pressure sodium lamps from 60 Hz possibly have a connection to headaches, distraction, fatigue, annoyance and lower productivity (Lehman, et al., 2011). Lehman, et al. further explains the concern about that an increasingly popularity of LED-lighting follows possible flicker, due to various forms of pulse width modulation in many products. LED-luminaires needs to be carefully matched with a compatible dimmer.
The reason pulse width modulation is used are due to less thermal load, longer life-time and it is a simple dim-technique. LED-light sources has potential, but when planning for new lighting design it is important to highlight the importance of choosing right actuator (Hemphälä & Nylén, 2013).
2.3.3 OLED
Organic Light-Emitting Diode (OLED) is a LED with an emissive electroluminescent layer of organic compound that emits light in response to electric current (European Commision; Joint Reasearch Centre, 2014). OLEDs emits a ”pleasant” UV-free light with a high CRI-index (European Commision; Joint Reasearch Centre, 2014). OLED-technology enables the creation of extremely flat panels, which emits light evenly over a surface (Khanna, 2014).
A manufacturing challenge with OLED-panels is integrating them into functional luminaires. It is no clear analogy for OLED luminaire manufacturing compared with LED luminaire manufacturing which is more similar to conventional luminaire manufacturing, consumer electronics manufacturing and semiconductor manufacturing (European Commision; Joint Reasearch Centre, 2014). OLED will pilot a paradigm shift, creating surface-emitting planar sources, in the lighting industry, together with LED-lighting (Khanna, 2014). OLED is the only lighting technology creating the possibility for an embedded light-emitting surface and functions as either a lamp or luminaire (Khanna, 2014). It is also possible to change the OLED in a range of colour temperatures. OLED- lighting enables a new way of design, personalize and create novel lighting concepts for living environments, offices, public places and vehicles such as cars, buses, railways and airplanes (Khanna, 2014).
Other benefits with OLED-Lighting are; Less heat generation, because of the capability to, instead of operating at a higher luminous intensity, enlarge the luminous surface and creating the same luminous flux (Khanna, 2014). The light source can be placed closer to the task surface without having a glaring effect, due to OLEDs low brightness (European Commision; Joint Reasearch Centre, 2014)
The ability to create the OLED-surface transparent enables the lighting to be mounted on windows and both work as a source of daylight and as a luminaire at night time. OLED-lighting will in the future be mounted in ceilings and on walls (Khanna, 2014). Transparent OLEDs improves contrast, which simplifies viewing displays in bright sunlight and can be used in head-up displays, smart windows or augmented reality (European Commision; Joint Reasearch Centre, 2014).
2.4 Lighting planning
An effective approach to find good lighting solutions is a structured analyse of the needs of an activity and the knowledge about good lighting (Nylén, 2012). According to Nylén (2012) should a structured analyse of the lighting environment include:
Sufficient illuminance
Harmonic brightness distribution No blinding lights
Correct light direction Appropriate shadowing
Good light colour and colour rendering Good room climate
Some aspects that should be taken into account when planning lighting according to Renström et.al (2013) are:
Visual conditions for the user Esthetical conditions
Technical conditions Architectural conditions Economical aspects Environmental aspects
It is important for the user’s well-being and to be able to see that the visual conditions are well planned (Renström & Håkansson, 2013). Factors that enhance well-being are when the user is able to adjust the brightness in the lighting environment and a diverse lighting setting (Renström & Håkansson, 2013). Key is an appropriate colouring and that all surfaces are lighted (Renström & Håkansson, 2013).
It is important that the interior design, colours and the design of the lighting fixture have a harmonic impression together (Renström & Håkansson, 2013).
Different situations in the room requires different lighting environments. It is important with sufficient lighting, correct light sources and fixtures for all the situations in the room. (Renström & Håkansson, 2013)
Lighting have the ability to enhance and improve the design of the room (Renström & Håkansson, 2013). Good communication with the designer is important for the overall experience in the room (Renström & Håkansson, 2013).
Economical aspects needs to be taken into account in order to make the project realistic. The lighting environment should be both stimulating and energy efficient. (Renström & Håkansson, 2013)
The light sources and the fixtures are a part of our ecological system and needs to be environmental friendly (Renström & Håkansson, 2013).
Different working and living-environments need different sets of lighting. An important aspect when planning for lighting design is to determine the preferred level of quality. This could mean that only standards and requirements are important or that bringing a certain feeling to the environment is important. (Renström & Håkansson, 2013)
2.4.1 Lighting planning process
The lighting planning process according to Ljuskultur (2013) can be seen in Figure 2-8.
Figure 2-8, the Lighting planning process according to Ljuskultur (2013).
Specify
If nothing else is mentioned is the information in this chapter gathered from Ljuskultur (2013).
Initially when starting a lighting planning project it is important to define the stakeholders in the project, which can be people in several different working categories. Stakeholders can be; the client, project manager, lighting planner, architect, decorator, installer, electrician and the end-user. The tasks for each stakeholders is different and it is important with good communication (Renström & Håkansson, 2013). Initially in a lighting planning project the client together with lighting planner sets the goals and the requirements for the lighting.
Specify key activities and what the room is used for. If there is a need for an emergency lighting it should also be specified and which laws and regulations to follow.
The visual tasks should be specified and include information about in which planes, vertically, horizontally or angled they take place in. Also the visual
environment, with the working object, working area and the surroundings, should be planned to create the best visibility as possible.
Define working areas, their requirements and how they affect the rest of the room.
The visual experience should be specified to fulfil the client’s desired result both in visual and nonvisual aspects. It is important the lighting is coordinated together with the interior, the materials and the colours in the room for the overall experience.
It is important that the interior design, colours and the design of the lighting fixture have a harmonic impression together (Renström & Håkansson, 2013).
Specify the environmental goals and energy efficiency for the lighting. Try to make the lighting system as energy efficient as possible without effecting the visual experience.
Specify a budget for installation, energy during use, controlling and maintenance.
Make a time plan for the project and specify the projects different phases; analyse of the conditions, planning of the lighting system, evaluation, documentation and installation.
Analyse
If nothing else is mentioned is the information in this chapter gathered from Ljuskultur (2013).
After the lighting planning have been specified an analysis of the forced conditions should be done. Define all laws, physical conditions, economical and historical conditions which needs to be taken into account in the lighting planning. Check how well they corresponds to the clients requirements.
Analyse the general conditions for the lighting planning. Define what is flexible and what is set in the design, interior, daylight, character and which type of screens is used. Check how well they corresponds to the clients requirements.
The list of requirements includes the clients- and legal requirements. Also lighting recommendations. All requirements should be weighed after importance. The list of requirements should include parameters such as; lighting intensity, lighting distribution, contrast between working area and the adjacent and the peripheral areas, lighting intensity in ceiling and on walls., cylindrical lighting intensity, reflectance of surface and their colours, size and position of windows, the colour temperature of the light sources and their CRI, limitations of luminance, luminance ratio within the viewing field and requirements to shield from glare, also energy consumption.
Aesthetical and architectural requirements can’t be quantified but should be fulfilled as much as possible.
Plan
If nothing else is mentioned is the information in this chapter gathered from Ljuskultur (2013).
When all have been specified in the previous steps, it is time to evaluate the lighting conditions and decide light sources, fixtures and controlling of the lighting system in this phase in the lighting planning process. Calculations for the lighting and the energy consumption should be done together with evaluation of the design and an economical assessment of the project and a maintenance plan is created.
Document
If nothing else is mentioned is the information in this chapter gathered from Ljuskultur (2013).
The documentation from planning the lighting system, blueprints and maintenance plan is compiled when they are approved of the client. The documentation should be so extensive and can be used for inspection assessment.
Evaluation
If nothing else is mentioned is the information in this chapter gathered from Ljuskultur (2013).
New lighting should be evaluated to check if the lighting works accord to the lighting planning. Existing lighting should be evaluated to make sure requirements for good lighting is fulfilled. New lighting systems require more extensive evaluation than existing lighting.
When evaluating the visual environment in the truck cab the questions in Appendix 8 – Visual/Physical – Conditions, with inspiration from Renström & Håkansson (2013) and Ljuskultur (2013), can be used as a checklist. When evaluating the visual condition an advantage is to use a lux- and luminance meter, but first evaluating the overall experience by looking end being in the room (Renström & Håkansson, 2013).
2.5 Product development process
The Front-End process is an iterative process used during the concept development in a product development process and is developed by Ulrich & Eppinger (2008), see Figure 2-9. During all phases are also the result and
knowledge from an economic analysis, benchmark, prototypes and models input for all phases (Ulrich & Eppinger, 2008).
Figure 2-9, concept development process developed by Ulrich & Eppinger (2008).
The mission statement is the result from the planning phase of the project and contains specification for the targeted market, business goals, key assumptions and constraints. (Ulrich & Eppinger, 2008)
The first phase in the development process is to identify customer needs and to list them in a hierarchy of which statements are important or not. (Ulrich & Eppinger, 2008)
In the second phase the development team establish a target specification, which is a technical translation of the customer needs. The result is a target specification list and each specification has a metric, a marginal and ideal value. (Ulrich & Eppinger, 2008)
With the target specification in mind the product development team generates product concepts thoroughly. The concept generation begins with clarifying the problem and dividing it into sub problems. The search for solutions and can be both internally and externally. When searching for solutions externally can include interviewing lead users, consult experts, search for patents, benchmark. When searching for solutions internally can be either individual or in group sessions. A combination of individual work and group sessions are ideal. Group sessions are critical for creating consensus, communicating information and refining concepts. (Ulrich & Eppinger, 2008)
The number of solutions is narrowed down and promising concepts are selected in a structured way and the concepts are evaluated how well they fulfil the customer target specification. Some concepts may be further developed before being selected. (Ulrich & Eppinger, 2008)
The selected concepts are further refined and tested to ensure they fulfil the target specification. Iteration is possibly needed. (Ulrich & Eppinger, 2008)
After further refinement of the concepts the final specification are set for the product. (Ulrich & Eppinger, 2008)
In the last phase of the concept development process the downstream development for the project are planned. (Ulrich & Eppinger, 2008)
2.6 Driving and rest periods for truck
drivers
There are several restrictions regarding the truck drivers driving and rest periods and are described in the following section. Examples of how the schedule during a week can look like can be seen in Figure 2-10. (Transportstyrelsen, 2015)
2.6.1 Daily rest
Each 24-hour period needs to have one daily rest. The duration of a normal daily rest is 11 hours. A reduced daily rest is 9 and the daily rest can be reduced maximum three times during a working week. A daily rest can also be divided into two periods the first period of 3 hours and the latter 9 hours (3+9hours). (Transportstyrelsen, 2015)
2.6.2 Driving time
Registered driving time is the time when the driver is driving the truck. The daily driving time is between two daily resting periods and is normally 9 hours, or maximum 10 hours two times a week. The maximum driving time during a week is 56 hours and during a two week period 90 hours. (Transportstyrelsen, 2015)
2.6.3 Resting time
During the resting time the driver is not allowed to do anything work related. After a 4.5 hour driving period a 45 minutes break is mandatory. The break can be divided into 15+30 minutes breaks and the latter break needs to be at least 30 minutes. When resting in the cab the truck needs to be still and equipped with suitable resting equipment. (Transportstyrelsen, 2015)
2.6.4 During a 24-hour period
A truck driver is allowed to drive for maximum 4.5 hours at a time, before taking minimum a 45 minutes break. The driver can choose to split the break during these 4.5 hours into two periods (15 min + 30 minutes). A new 4.5 hour period starts to count after the longer period, 45 minutes or 30 minutes. (Transportstyrelsen, 2015)
The truck driver can drive 9 hours before taking a daily rest. Each 24-hour period needs to have a daily rest. Additionally applies a rule which the driver can make an exception two times a week and drive for 10 hours before taking a daily rest. (Transportstyrelsen, 2015)
2.6.5 During a week
The working week for a truck driver can be maximum 6 days in a row, before a weekly rest is mandatory. A normal weekly rest is at least 45 hours long, but an option is a reduced weekly rest of 24 hours. When having a reduced weekly rest the driver needs to add the time missing during the reduced weekly rest to another daily rest (9hours+lost time during reduced weekly rest), before the end of the third week after the reduced weekly rest. (Transportstyrelsen, 2015)
2.6.6 Multi drivers
When driving with multiple drivers a daily rest of 9 hours needs to be taken during a 30 hours period. The 30 hour period begins when the first driver starts to drive after a daily- or a weekend-resting period. When driving as multiple drivers the co-driver must be on board during all hours except on hour in the beginning of the driving period. The co-drivers time is registered as available. (Transportstyrelsen, 2015)
Figure 2-10, examples of truck driver schedules (inspired by the regulations on Transportstyrelsen (2015)).
3 Methodology
This chapter contains the methodology and the process of this thesis. The methodology is based on user-driven design. The process can be seen below in Figure 3-1. In the first phase focus is planning and to gain knowledge about the user, the product and to study basic relevant literature. The first phase will result in an analysis. The second phase is the main which is an iterative process with the first analysis as input. The third phase is a ramp-up phase as a result of the final two analysis with a guide for lighting design (see Figure 3-1).
3.1 Product and user knowledge
The first aim was to get a better understanding of the product and the user; the Scania truck and its driver. To be able to understand the context in which the user interact and work, studies were made to widen product knowledge, i.e. learn more about the trucks, its environment and lighting design. Courage & Baxter (2005) stresses that the learning about a product and its domain and doing the "homework" before involving actual users is important for the researcher to know several basic facts: What are the available functions? Who are the competitors? Are there any known issues with the product? Who are the product's perceived users? These questions should be answered and are intended to aid in deciding what further research you want to perform.
3.1.1 Exploratory research
To be able to get an initial physical contact with the product and with no prior experience, a grab-and-test approach was used. An exploratory research is very flexible and spontaneous interactions and observations are encouraged (Hanington & Martin, 2012). This was done by first studying different truck's exterior and interior to get a feeling of basic measures and comfort, its expression etc. Studied trucks where from Scania's own existing product line such as the R, G and P-series. The study was performed at Scania, in daylight and in a free exploratory manner. Basic functions in the cab were tested such as control of light switches and visual comfort was discussed by sitting in the truck performing basic tasks.
3.1.2 Test drive at Scania demo centre
A test drive session was attended with trucks and busses at Scania's demo centre in Södertälje. The demo centre allows visitors to drive with Scania vehicles along a test road where you are challenged to handle vehicle and cargo through up- and downhill, sharp turns and parking. The authors test drove heavy cargo long-haulage trucks and also buss.
3.1.3 Living in the truck, an empathy study
An empathy study was performed in a Scania truck, a Scania R480 Long-haulage with accommodation for two people with cooking equipment, storage, fridge/freezer and bunk beds. The study was initiated through the authors need to empathise with truck drivers in a part of their daily life. The test was conducted from late afternoon until early morning. The purpose was not only to empathise with truck drivers but to understand issues with the existing interior lighting. The study was made in line with a method called AEIOU, which stands for Activity, Environment, Interactions, Objects and User (Hanington & Martin, 2012). The method AEIOU is an organizational framework of elements that needs to be coded during observations. The methods two primary functions are to analyse the objectives and issues of a client by developing elements and to code data (EthnoHub, 2015). Even though the method has a pre-set of elements, further analysing can be made (Hanington & Martin, 2012). It works as a guide during the observation and
helps the researcher to make sure nothing is forgotten. Elements which is coded during observations are; activities, environment, interactions, objects and users according to (EthnoHub, 2015):
Activities are the actions and processes which is done to accomplish some sort of goal. Describe the pathway and specific actions and processes during these activities.
Environments are the arena in which the activities takes place. Describe the atmosphere and the function of the context. Which spaces are shared and which spaces are individual are relevant questions.
Interactions between elements are the building blocks for the activities. The elements could be between a person and someone or something else. Objects are the building blocks of the environment and relates to the
activities somehow. Are the objects used as they are intended or are their function, meaning and context changed?
Users are the people who are being observed. Who is the user? What are the user’s preferences and needs and how is their behaviour? What values and prejudices do they have?
Prior to the study a protocol was made for several intended activities to be studied. The protocol is based on experience from the interview with a driver and the exploratory research where main focus was to study several possible activities. Also the lights that were used during each activities was notified. During observation for each activity the protocol was used, notes and photos were gathered.
3.1.4 Benchmark
Benchmarking is about learning about your competitors and their advantages/disadvantages regarding a similar product or a surrogate product. A benchmark can provide a rich source of ideas for the product and production design and successful positioning of a new product (Ulrich & Eppinger, 2008). The benchmarking was conducted by comparing lighting environments in trucks from other manufacturers. The trucks studied was long haulage trucks. The benchmark was conducted in an exploratory manner. The comparisons was made from unique features, design weaknesses and design strengths.
